Barnes & Noble is dropping its Nook e-reader prices for a limited period leading up to Mother's Day, May 13 for its Nook Simple Touch and Nook Color. The price drops come on the heels of news that B&N will take a $300 million investment from Microsoft to do battle against Amazon and Apple and craft a Nook app for Windows 8.

From May 1 to May 12, Barnes & Noble says it'll knock $20 off its Nook Simple Touch as well as the higher-priced Nook Color. The black and white Simple Touch typically goes for $99 ($79 during the sale, or 20% off), while the Color model retails for $169 ($149 during the sale, or 12% off). As a bonus, the company says it'll throw in a Nook gift bag "made of matte art board laminated for extra strength" and "grosgrain handles ... anchored by sturdy powder-coated metal grommets." The bags usually go for $3.95 each.

In Barnes & Noble's Nook lineup, which consists of four devices, the Nook Simple Touch with 6-inch screen is at the bottom of the pile -- it's the entry-level model without a backlight. The model people seem most interested in (it's backordered on Barnes & Noble's website until May 7) is the Simple Touch with GlowLight is not discounted and will run you $139. Also not discounted is the $250 Android-based Nook Tablet tablet that is comparable to the Kindle Fire.

If you want to give Mom the gift of color, for books that support it, the Nook Color with 7-inch screen gets the job done, but it's also a notable step back from Barnes & Noble's flagship Nook Tablet ($199, not discounted). The Nook Tablet is faster, has a few hours extra battery life, weighs a tick less and includes a microphone (for a "Read and Record" book feature). But here again, you're looking at a significant price differential ($50), making it a question of whether Mom really needs those extras.

What about Amazon's Kindle e-reader lineup, the obvious alternative in terms of popularity? Amazon hasn't said yet whether it'll discount its devices for Mother's Day, so at the moment you're looking at $79 for Amazon's baseline black and white Kindle, $99 for the Kindle Touch, and $199 for the Kindle Fire -- comparable to Barnes & Noble's Nook Tablet.